Recursive Query Facilities in Relational Databases: A Survey

Przymus, Piotr; Boniewicz, Aleksandra; Burzańska, Marta; Stencel, Krzysztof

doi:10.1007/978-3-642-17622-7_10

Cited by 16 publications

(9 citation statements)

References 4 publications

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“…According to [2] this query conforms to SQL dialects of most database managements systems that support SQL:1999 recursion. Unfortunately, some database systems do not implement such queries.…”

Section: Recursive Data Structuresmentioning

confidence: 98%

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Unrolling SQL: 1999 Recursive Queries

Boniewicz

Stencel

Wiśniewski

2012

Communications in Computer and Information Science

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Abstract. Hierarchical and graph data structures are common in practical application development. In order to query such data, one can use SQL:1999 recursive queries based on Common Table Expressions. Nowadays, numerous relational database management systems implement them. However, some popular systems, e.g. MySQL, still lack this useful feature. In this paper we show three methods to circumvent this situation: (1) the direct loop, (2) horizontal unrolling and (3) vertical unrolling. We analyze them and present a report on tests of their efficiency. We also describe our implementation of these methods as a prototype extension to Hibernate, a major object-relational mapping system. This extension allows running SQL:1999 recursive queries directly from an application code, even when the underlying DBMS does not support them.

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Section: Recursive Data Structuresmentioning

confidence: 98%

“…In 1999 it resulted in augmenting the SQL standard with recursive queries based on Common Table Expressions. Such queries have already been implemented in a significant number of database systems, both commercial and open-source [2]. Researchers developed optimization methods for recursive queries [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Unrolling SQL: 1999 Recursive Queries

Boniewicz

Stencel

Wiśniewski

2012

Communications in Computer and Information Science

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“…Until them only a few DBMSs had implemented such querying facilities. A survey on the implementations of SQL:1999 recursion can be found in [2].…”

Section: Related Workmentioning

confidence: 99%

“…Another paradigm was voted into SQL:1999 based on recursive Common Table Expressions. It has been implemented in numerous database systems [2], while the academia worked on optimization methods for such queries [3,4,5]. However, there are still database systems whose SQL dialect does not include any recursion in queries.…”

Section: Introductionmentioning

confidence: 99%

On Materializing Paths for Faster Recursive Querying

Boniewicz

Wiśniewski

Stencel

2014

Advances in Intelligent Systems and Computing

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Abstract. Recursive data structures are often used in business applications. They store data on e.g. corporate hierarchies, product categories and bill-of-material. Therefore, recursive queries as introduced by SQL:1999 or formerly implemented by Oracle constitute a useful facility for application programmers. Unfortunately, recursive queries are not implemented by a number of database systems with MySQL as the most profound example. If an application has such a database as the backend storage, recursive queries will be usually hard-coded at the client side. This is not efficient. In this paper we propose using redundant data structures to answer recursive queries quicker. Such structures must be synchronized in response to updates of data. This means a significant processing overhead for updates. We present experimental evaluation to show loses and gains caused by our solution for various usage scenarios. They prove the feasibility of our proposal. We show our proof-of-concept implementation as a part of the Hibernate framework. Thus, application programmers are separated from all internals of necessary database objects and triggers. These are created automatically by Hibernate generators.

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“…Recursive queries have been introduced into the SQL languages according to ANSI SQL-99 standard in order to facilitate the access of hierarchical data, leading to more elegant and better performing applications [21]. This can be implemented by defining either a Recursive Common Table Expression (RCTE) or a Recursive View.…”

Section: Introductionmentioning

confidence: 99%